Surface sweeping machine equipped with gutter brush

ABSTRACT

A mobile road or like surface sweeping machine has a gutter brush and a brush driving hydraulic motor carried on a supporting structure which is mounted on the machine frame for compound vertical and horizontal swinging movements from a stowed position, with the brush in close to the machine frame and elevated and out of contact with the ground surface, to an extended operating position relatively wide of the frame and in pressure engagement with the surface to be swept. The brush rotates about a generally vertical although slightly tilted axis. A single power operated means, a hydraulic ram, operates the supporting structure to produce the compound vertical and horizontal swinging of the latter. When the brush encounters increased resistance to rotation, for example due to built-up or heavy debris, the pressure of the hydraulic fluid at the motor inlet increases, and the ram responds to that condition by forcing the brush into greater pressure contact with the surface, thereby ensuring greater capability of sweeping the obstruction.

Young, deceased 1 Feb. 12, 1974 SURFACE SWEEPING MACHINE EQUIPPED WITHGUTTER BRUSH [76] Inventor: Bernard W. Young, deceased, late of PD. Box2368, Waco, Tex. by Sophie Young, e'xecutrix [22 Filed: Sept. 15, 197221 Appl. No.: 289,453

[52] US. Cl....' 15/87, 15/340 Primary ExaminerEdward L. RobertsAttorney, Agent, or FirmBaldwin, Wight & Brown [57 ABSTRACT A mobileroad or like surface sweeping machine has a gutter brush and a brushdriving hydraulic motor carried on a supporting structure which ismounted on the machine frame for compound vertical and horizontalswinging movements from a stowed position,

with the brush in close to the machine frame and elevated and out ofcontact with the ground surface, to an extended operating positionrelatively wide of the frame and in pressure engagement with the surfaceto be swept. The brush rotates about a generally vertical althoughslightly tilted axis. A single power operated means, a hydraulic ram,operates the supporting structure to produce the compound vertical andhorizontal swinging of the latter. When the brush encounters increasedresistance to rotation, for example due to built-up or heavy debris, thepressure of the hydraulic fluid at the motor inlet increases, and theram responds to that condition by forcing the brush into greaterpressure contact with the surface, thereby ensuring greater capabilityof sweeping the obstruction.

29 Claims, 10 Drawing Figures LEFT SIDE Patented Feb. 12, 1974 3,7@@,%1

4 Sheets-Sheet 2 LEFT SIDE Patented Feb. 12, 1974 I 3,7,9W

4 Sheets-Sheet 55 FROM 0 LEFT SIDE Patented Feb. 12, 1974 4 Sheets-Sheet4 SURFACESWEEPING MACHINE EQUIPPED WITH GUT-TIER BRUSH well known. Insome, a gutter brush is mounted on a support which can be swung by oneoperating means from a stowed elevated position under or close in to themachine frame to an extended position outwardly of the frame, and whichcan be lowered by another operating means from its extended position topress the brush against the surface to be swept.

An object of the present invention is to provide a machine of thegeneral class referred to embodying constructional improvementsresulting in efficiency of operation, and simplicity of controlling thepositioning of the brush.

Another object is to provide such a machine in which a single poweroperated means effects compound vertical and horizontal movements of abrush supporting structure to move the brush from a retractd andelevated stowed position outwardly from the machine frame and downwardlyinto engagement with the ground surface in one continous movement, andof course to move the brush reversely to stowed position.

A further-object is to provide equipment of the kind outlined abovehaving means for precisely adjusting the amount of pressure exerted bythe brush downwardly on the surface being swept.

A further object is to provide means for causing increased downwardpressure to be exerted on the surface being swept automatically inresponse to increased resistance to rotation of the brush, such as wouldbe encountered when the brush contacts a build-up of debris or otherobstacle, the so applied increased downward pressure of the brushimproving its ability to sweep the debris or obstacle instead of raisingabove it or otherwise yieldingto it. 7

Other objects of the invention will become apparent from a reading ofthe following description, the appended claims, and the accompanyingdrawings, in which:

FIG. 1 is a side elevational view of a mobile road or like surfacecleaning machine provided with equipment embodying the invention;

FIG. 2 is a schematic top plan view of the machine shown in FIG. '1,showing some parts in outline only;

FIG. 3 is a perspective view of a gutter brush equipment mounted on avehicle side frame member, the view being from above and from outwardlybeyond the left side, i.e., the drivers side of the vehicle. Thebrushand its supporting structure are shown in an intermediate position,that is between a fully stowed position in close to the vehicle frameand an extended position for operation in gutters;

FIG. 4 is an exploded perspective view of a supporting structure, and ahydraulic motor and rotatable brush mounted thereon;

FIG. 5 is a perspective view similar to FIG. 3 but showing thesupporting structure, hydraulic motor and brush in the two extremepositions, viz, POSITION I retracted to lift the brush from the groundand to stow it close to the vehicle frame, and POSITION II in which thebrush has been swung out laterally with compound downward movement tobring it into contact with the surface to be cleaned;

FIG. 6 is a schematic diagram of a hydraulic circuit for operating thebrush rotating motor and brush positioning means by which the brush isselectively moved to its POSITION I and POSITION II indicated in FIG. 5.In FIG. 6, valves in the hydraulic circuit are set for moving the motorand brush to POSITION II in which 7 the brush is extended laterally andis moved downwardly into pressure engagement with the ground and formaintaining the motor and brush in that position during operation;

FIG. 7 is a detailed cross-section on the line 77 of FIG. 6;

FIG. 8 is a detailed cross-section on the line 8-8 of FIG. 6;

FIG. 9 is a schematic hydraulic circuit diagram according to FIG. 6, butwith the valves set for retracting the brush inwardly toward the vehicleand upwardly out of contact with the ground to POSITION I andmaintaining it in that position; and

FIG. 10 is a simplified hydraulic circuit diagram showing hydraulicequipment for operating two gutter brushes, one on each side of thevehicle.

The invention is illustrated as being embodied in a mobile road, streetor the like surface cleaing machine conforming generally to that shownin US. Pat. No. 3,512,206 granted to Bernard W. Young May 19, 1970 forAIR FLOW SURFACE CLEANING APPARA- TUS. As shown in FIGS. 1 and 2, themachine includes a basic truck vehicle V having a chassis frame Fincluding longitudinal side members 1, 1' respectively at the left ordrivers side of the vehicle and at the right side thereof. A motorhousing is indicated generally at 2, and a cab is indicated at 3. Themachine includes a pick-up head 4 which extends transversely under thevehicle frame F above the surface to be cleaned. As explained in US Pat.No. 3,512,206, a blower S delivers air under pressure through a duct 6into the pick-up head 4. Air is drawn from the pick-up head through asuction duct 7 into a bin 8 in which solids, dust, etc., picked up fromthe surface are deposited. The blower 5 takes its intake through a duct9 which commumicates with the bin 8 whereby the latter is maintainedunder suction. No further details of the main pick-up equipmentincluding the head 4 need be described here since they are fullydescribed in the aforesaid US. Pat. No. 3,512,206 and do not inthemselves constitute any part of the present invention. In fact, gutterbrush equipment according to the present invention may also be used inassociation with other types of main brushing equipment including, interalia, conventional rotatable cylindrical brushes which extendtransversely across the vehicle. In any case, the gutter brush equipmentaccording to the present invention is especially useful for reaching outand sweeping surfaces adjacent to curbs or walls or such verticalsurfaces which cannot be reached by the main cleaning devices such asthe pick-up head 4. The gutter brush according to the present inventionthus supplements the action of the pickup head 4 by directing debris anddust inwardly toward the vehicle into position where it can be picked upby the pick-up head 4. Although a single gutter brush equipment mountedat one side of te mobile machine may be very useful in somecircumstances, it generally is desirable to provide two such equipments,one on either side of the machine, so as to provide for cleaning asurface regardless of which side of the machine is run close to thegutter, wall or the like. The present invention is illustrated asincluding two gutter brushes mounted respectively on opposite sides ofthe machine, but since they are the same other than one being a mirrorimage of the other, only one gutter brush equipment, namely that mountedat the drivers side of the machine, will be described in detail.

BRUSH AND MOTOR MOUNTING Referring especially to FIGS. 1-5, an anglemounting bracket is secured to the left frame side member 1 by a bolt 11passing through a hole 12 in the bracket and a hole 13 in the member 1,and by a bolt 14 passing through one of three holes 15 in the bracket 10and a hole 16 in the frame member 1. For achieving a purpose later to beexplained, the bolt 14 may be passed through any one of the three holes15 in the bracket 10 to give the latter a desired tilt and also to tiltthe brush.

A brush positioning supporting structure means generally designated ST,mounted on the bracket 10, carries a rotary hydraulic motor M which inturn carries a disk-like brush B. The brush B is mounted for rotationcoaxially with the motor M on a substantially or generally vertical butsomewhat tilted axis.

The supporting structure ST includes a boom 17 which is mounted forhorizontal and vertical pivotal movement at a first location designatedLl on the bracket 10. A plate 17a mounts the motor M and brush B at asecond location L2 on the boom 17. Power operated force applying means,as shown a double acting ram 18, is mounted for horizontal and verticalpivotal movements at a third location L3 on the bracket 10. The ram 18is connected to the boom 17 at a location remote from the first andthird locations L1 and L3 respectively, and relatively adjacent to thesecond location L2.

The operating means, i.e., the hydraulic ram 18, is of the differentialacting type and includes a cylinder component 19, a double acting pistoncomponent 20 reciprocal therein, and a piston rod 21. The effectivepressure responsive area of the piston 20 at the face thereof from whichthe rod 21 extends is less than the effective pressure area on theopposite face. Thus, if equal unit pressures are applied to thetwoopposed faces of the piston 20, the net force will be effective toextend the rod 21. In the form shown, the rod component 21 is connectedto the boom 17 by a screw 22 extending through a hole in the flattenedend of the rod and into a lug 23 on the boom.

Considering more particularly the mounting of the boom on the framebracket at location L1, a bearing post 24 is mounted on the bracket 10to provide upper and lower lugs 25 formed with aligned holes 26. A crossmember 27 is provided with aligned vertical pintles 28 journalled in thelug holes 26 and with horizontal pintles 29. The inner end of the boom17 is formed as a clevis having horizontally spaced lugs 30 apertured toreceive the horizontal pintles 29 of the cross member 27. It is apparentthat by virtue of the connections at the location L1 the boom 17 mayhave compounded horizontal swinging movement and vertical swingingmovement.

The cylinder component 19 may also have compounded vertical andhorizontal swinging movements about the location L3. A bearing post 31mounted on the bracket 10 is provided with horizontally spaced lugs 32formed with holes 33. A cross piece generally designated 34 is formedwith horizontal pintles 35 which are received in the holes 33 in thelugs 32. The cross piece 34 is also provided with vertical pintles 36which are received in holes 38 in spaced ears 37 fast with the cylindercomponent 19.

Inasmuch as the piston component 20 and rod 21 can rotate about theircommon axis in the cylinder 19, there may also be a compound movement ofthe cylinder component 19 with respect to the boom 17, such movementincluding pivoting about the bolt 22 and also twisting or rotating ofthe piston 20 and rod 21 in the cylinder 19 as may be required to avoidbinding.

Closely associated with and in a sense functioning as a part of thesupporting structure ST is a coiled tension spring 39 connected at oneend to the frame bracket 10 by an anchor 40 and connected at its otherend to an adjusting screw 41 threaded into a lug 42 on the boom 17adjacent the motor and brush mounting. The spring biases the supportingstructure ST to swing about the location L1 vertically and horizontallyto move the brush in close to the frame member 1 and move it upwardlyout of contact with the ground surface, this being POSITION I requiredfor moving the equipment while not using it for brushing. The spring 39is, however, yieldable to permit the brush to be swung outwardly anddownwardly into operating position as explained later.

The hydraulic circuit illustrated in FIGS. 6 and 9 provides power foreffecting the vertical and horizontal swinging of the boom required forselectively positioning the brush in stowed position in close to themachine frame and up out of contact with the ground (POS- TION I and toextend it to operative position in contact with the ground (POSITIONII). In the preferred arrangement, pressure is applied to both sides ofthe piston 20 to swing the brush outwardly into operative position anddownwardly, and is applied to only the smaller effective area side ofthe piston 20 to return the brush to its stowed position. Controlling ofthe circuit for performing these operations will be explained later, itbeing sufficient for the present to consider only broadly the twocontrolling conditions, namely one in which the differential actinghydraulic ram holds or returns the brush to stowed position and theother in which the ram extends the brush to operative position. Itshould be noted here that the spring 39 acts in concert with that forceon the ram piston 20 which tends to move the brush to its retracted orstowed position. Tightening the spring increases the vertical or liftingforce applied to the boom more than it increases the force tending toswing the boom in horizontally.

When fluid under pressure is applied to both sides of the piston 20, thepressure acting on the larger effective area side of the piston extendsthe latter with the result that the boom 17 is swung outwardly anddownwardly from POSITION I to POSITION II as shown in FIG. 5.

This will position the brush relatively widely spaced outwardly from thevehicle so as to work close to a curb or wall and at the same time thebrush will be pressed downwardly into engagement with the ground. Thisextension of the ram is dominated by fluid pressure acting on the largereffective area side of the piston 20 even though this action is opposedboth by fluid pressure acting on the piston face of less effective areaas well as the tension of the spring 39. The tension of the spring 39may be adjusted by way of the adjusting .screw 41 so as to obtain theproper balance required for smooth extending and retracting operationsof the boom and brush. To stow the boom and brush in nonoperatingposition, fluid under pressure is applied to only the rod face of thepiston 20, the opposite face of the piston being exposed to exhaust. Thepressure acting on the rod face of the piston, augmented by the force ofthe spring 39, returns the boom 17 to POSI- TION l.

The compound horizontal and vertical movement of the brush which takesplace during these settings may be understood clearly be referring tothe diagrammatic trace of a point A on the common axis of the hydraulicmotor M and brush B shown in FIG. 5. In moving about a center O of thecross piece 27 at the location Ll, the point A traces a'path Pl on animaginary sphere having its center at O. The vertical projection of thepath P1 on the ground is shown at P2. The dimension indication Hrepresents the height of the point A above the ground when the ram isretracted and the partsare stowed (POSITION I). Comparison of thedimension h with the dimension H shows the degree of lowering of thepoint A toward the ground when the ram is extended to swing thesupporting structure ST to POSITION II.

In connection with the performance of the compounded vertical andhorizontal swinging movements of the boom 17, it is pointed out that theram l8 is connected for vertical and horizontal pivotal movements to theframe bracket 10 at location L3 which is spaced above and inwardlytoward the frame member 1 from the location L1 at which the boom isconnected for vertical and horizontal swinging movements to the framebracket 10. It is also pointed out that the spring anchor 40 ispositioned between and above locations L1 and L3.

It is preferred that the circular brush, which is rotatable about asubstantially vertical axis, be tilted slightly to the vertical so as toengage the ground initially and with greater force toward the front ofthe vehicle, this being well known with respect to gutter or the likecircularbrushes. The rear of the brush with respect to the travellingframe preferably is clear of the ground or just barely touches it sothat the brush rotating in the.

direction of the arrow a in FIG. 2 will move dirt, debris and the likeinwardly toward the machine in front of the .main pick-up equipment 4.The amount of tilt of of the piston of the ram 18 to swing the brushoutwardly' relatively wide of the frame F and downwardly into operatingposition in which the brush is held in the generally vertical axis ofthe brush required may be adjusted by selecting which of the three holes15 in the frame bracket 10 isto be aligned with the hole 16 in the framemember 1 and secured by the bolt 14.

HYDRAULIC CIRCUIT pressure engagement with the surface being swept. Themotor M and ram 18 are included in the hydraulic circuit also comprisinga supply and exhaust tank T, a pump P, an operations control valve OCV,a sequence valve SV, a rate-of-flow valve RFV, and conduit connectionsdescribed below. The pump is not of the constant volume delivery typeand its delivery pressure can adjust to the load. A conventional stockpump is used.

The operations control valve OCV may be a conven-' tional four-way valvehaving a casing 42 formed with ports 43, 44, 45 and 46, and a rotor 47formed with arcuate passages or long ports 48, 49 and a straightthroughpassage 50. Detent or like means, not shown, hold the rotor 47releasably in the selected set position. The sequence valve SV, socalled because it in part controls the sequence of swinging thesupporting structure ST outwardly and downwardly and applying increasedpressure to the brush at certain times, includes a body 51 which isbored to receive a cyindrical insert 52 threaded into the body at 53.The inner end portion of the insert 52 is of reduced outer diameter andis hollow and closed at its upper end by a transverse wall 53 providedwith an O-ring 54 engaging the wall of the body bore to prevent flow offluid past the outside of the wall 53. A valve seat fitting 55 isthreaded into the end 53 to provide communication between the body boreabove the wall 53 and a chamber 56 within the hollow of the insert 52,the chamber extending outwardly partially to surround the insert 52within the body bore wall. The communication provided by the valve seatmember 55 is controlled by a poppet valve 57 device urged on to the seatby a spring 58, the loading of which may be adjusted by turning a screwplug 59. A series of relatively small holes 60 extending through thecylindrical wall of the insert 52 adjacent the end wall 53 and a seriesof relatively larger holes 61 extending through the insert cylindricalwall spaced downwardly from the holes 60 provide communication betweenthe chamber 56 in the hollow of the insert and the surrounding chamberextension between the outside of the cylindrical insert wall and thewall of the bore in the body 51.

When the operation control OCV is set as shown in FIG. 6, the pump Pdelivers fluid through a main supply conduit 62 through operationcontrol valve OCV ports 43, 48 and 44 to a primary service conduit 63into the chamber 64 in the body of the valve SV above the insert wall53. Fluid under pressure is applied from the chamber 64 through a branchservice conduit 65 and rate-of-flow valve RFV to the head end of the ram19, that is the cylinder end in which the piston faceof larger effectivearea is presented. The conduit 65 bypasses the poppet valve device 55,57. The rate-of-flow control valve RFC may be any form of needle orother throttle valve design which is constantly open and functions tocontrol the rate of fluid flow through the .branch conduit 65 to the ramas distinguished from controlling pressure per se. It will be noted thatwhen the poppet valve 57 element in the sequence valve SV is open asshown in FIG. 6, there is relatively open communication between theprimary service conduit 63 and the head end of the ram cylinder save, ofcourse, the effect of the valve RFV in controlling rate of flow to thatend of the cylinder.

Pressure acting from the primary service service conduit 63 in the valvechamber 64 and valve seat 55 passage opens the poppet valve 57 againstthe loading of the spring 58, permitting fluid under pressure to flowinto the chamber 56, and out through the holes 60 and 61 into the outerchamber between the insert 52 and the valve body bore wall. From thesechambers, fluid under pressure flows through a conduit 66 to the inletside of the motor M, driving the latter to rotate the brush. Pressurefluid is discharged from the motor through a motor discharge conduit 67and through passage 68 in the valve body 51 to return to the tank T viaoperation control valve ports 45, 49 and 46 and an exhaust conduit 68opening into the tank.

Opening of the poppet valve 57 also enables the application of pressurethrough a branch conduit 69 to the rod end of the ram cylinder, that isthe end at the side of the cylinder of relatively smaller effectivearea. As previously stated in the description of the supportingstructure ST and its operation by the ram 18, when fluid is applied toboth sides of the piston the pressure exerted upon the piston face oflarger effective area dominates and extends the ram to swing thestructure ST outwardly and downwardly. The net force with which thebrush is pressed against the surface being swept may be adjusted byvarying the hydraulic pressure acting in the ram. This may be done byadjusting the loading on the spring 58. Increasing the load on thespring 58 and thereby requiring more pressure to open the poppet valve57 increases the net effective hydraulic pressure acting on the ram sothat the brush is forced downwardly to exert increased pressure on thesurface being cleaned. Decreasing the load on the spring 58, for exampleby turning the adjusting plug 59 outwardly, has the reverse effect. Thepressure exerted by the brush on the surface being swept can also beadjusted by varying the tensile loading of the spring 39 as previouslydescribed. Thus, it is possible to provide a very precise regulation ofthe pressure exerted by the brush on the surface being swept. This isquite an important factor since pressure requirements'may changeaccording to the nature of the ground surface itself, the heaviness oramount of accumulation of trash or debris, or the relatively new orrelatively worn condition of the brush bristles or fingers.

In order to return the supporting structure ST, motor M and brush B tostowed POSITION I with the brush elevated and in close to the machineframe F, the rotor of the operations control valve OCV is turned to theposition shown in FIG. 9. Pressure fluid will then be delivered throughthe valve OCV ports 43, 48 and 45 to the motor discharge conduit 67 andthence back reversely through the motor M and through the branch conduit66 to the chamber 56 in the sequence valve SV. Pressure of this fluid inthe chamber 56 will close the poppet valve 57 on the seat 55, the valve57 then acting as a check valve preventing further flow through thevalve seat. Fluid flowing reversely from the motor M through the branchconduit 66 will pass up through the chamber 56 into the branch conduit69 and thence into the rod end of the ram 18. At the same time, theopposite end of the ram cylinder will be open to exhaust through thebranch conduit 65, valve RFV, the chamber 64, the primary serviceconduit 63, the operation control valve ports 44, 49 and 46, and theexhaust conduit 68. Thus, no effective fluid pressure is exerted on thehead end of the ram piston while pressure is continued to be exerted onthe rod end of the piston providing a force which, together with thatexerted by the spring 39, moves the structure ST to swing inwardly tothe frame 1 and upwardly to position the brush above and out of contactwith the swept surface. The valve RFV limits the speed of retraction ofthe ram and returning of the structure ST to POSITION I.

The rotor of the operation control valve OCV may be set to position thestraight-through passage 50 to connect the ports 43 and 46 so that pumpdischarge flowing through the main supply conduit 62 will be returnedthrough the exhaust conduit 68 to the tank T, the pump then runningidly. At this setting of the valve OCV, means, specifically lands on thevalve body 47, block off both ports 44 and 45 so that fluid is trappedin both ends of the ram cylinder 19 and the ram piston 20 will be heldagainst movement so that the supporting structure ST will be maintainedin the position which it occupied when the rotor of the valve OCV wasset to block off the ports 44 and 45.

An important feature of the present invention is the hydraulic circuitrelation of the brush driving motor M and the power operated ram 18which results in pressing of the brush against the surface being sweptmore firmly when the brush encounters built-up debris or an obstacle orthe like producing increased resistance to rotation of the brush andconsequent increase in the motor torque. When the brush B encounterssuch an obstacle, the torque required to keep rotating the brushincreases and this causes an increase in pressure in the branch conduit66 leading to the motor inlet and also an increase in fluid pressure inthe valve chambers 56 and 64 and branch conduits 65 and 69 leading tothe ram 18. The result is that greater or increased net effectivehydraulic pressure force is applied to the ram to cause the brush topress against the surface being swept with increased pressure whichensures better capability of dislodging the encountered obstacle orbuilt-up debris and sweeping it in front of the main pick-up head 4. Theram 18 responds to the increased pressure condition in the hydraulicinput to the motor for applying this increased pressure of the brush onthe surface. It is emphasized that when the brush encounters such anobstacle the hydraulic circuit and its components react to cause thebrush to be pressed downwardly more firmly in contact with the surfacebeing swept rather than to shirk the job and relieve pressure of thebrush against the surface to permit it to ride over the obstruction.Nevertheless, if the brush should encounter something more in the natureof an immovable obstruction such as a hard lump of concrete on thesurface or a vertical obstruction such as a post, the hydraulicconnections will permit the ram to be forcibly contracted by effortexerted mechanically on the brush or the supporting structure ST. Thus,the supporting structure and with it the brush and motor can be forcedinwardly and upwardly when encountering such a stubborn obstruction soas to avoid damage to the mechanism. Once the obstruction has beenpassed, as permitted by yielding of the structure ST, the latter will bereturned to its normal operating position without any adjustment of thevalves being required.

The foregoing description has reference to the gutter brush B, motor Mand cooperating mechanism and bydraulic parts and equipment foroperating the brush B mounted at the left or drivers side of themachine. Ordinarily a mirror image, or at least similar, counterpart ismounted at the right side. This is indicated in FIGS. 1 and 2 by showingsome right side parts designated by primed characters corresponding tothe left side designating characters. Thus, the right side parts includethe brush B, supporting structure S'T', ram 18', and so on.

FIG. shows diagrammatically how the pump P and tank T may servehydraulic systems for operating both left and right side brushequipments. Separate sets of valves, separate conduits, and separatehydraulic rams for the left and right sides are provided. The valves,the conduits, and the ram for the right side equipment are designated byprimed characters corresponding to the characters denoting the left sidecomponents.

Usually only one of the two sets of equipment (right and left side) isused, depending on whether the left or right side of the machine is torun close to a curb or gutter. Therefore, the hydraulic systems areoperable independently of one another by separate operation controlvalves OCV and O'C'V'. However, there may be times when it is useful toincrease the width of the swath being brushed irrespective of theproximity of a curb or wall. In such cases, the two gutter brushequipments may be operated simultaneously. In the form of machineillustrated, the total swath swept would be increased by the amount eachbrush is extended laterally beyond the adjacent end of the trailingpick-up head 4.

The construction illustrated and described includes the presentlypreferred embodiment of the invention, but it is intended that thedisclosure be illustrative rather than definitive, the invention beingdefined in the claims.

I claim:

1. A mobile road or like surface sweeping machine comprising a frame; abrush mounted on said frame for rotation in contact with the surface tobe swept; a motor for rotating said brush; brush positioning means formoving said brush downwardly to press on said surface; means fordelivering power to said motor; and force applying means associated withsaid power delivering means and connected to said brush positioningmeans for operating the latter to move said brush downwardly and beingresponsive to a condition in the input to said motor for applyingincreased force to said brush positioning means when said brushencounters built-up debris or an obstacle or the like with resultantresistance to rotation of said brush and running of said motor, saidapplication of increased force to the brush positioning means pressingthe brush with increased firmness against said surface thereby better toensure sweeping of the debris, obstacle or the like.

2. Machine according to claim 1 in which said motor and said forceapplying means are fluid pressure operated andin which said forceapplying means is responsive to an increase in pressure of fluid in thefluid pressure operated motor inlet supply for applying said increasedforce to said brush positioning means.

3. A mobile road or like surface sweeping machine comprising a frame; amotor; a rotary brush connected to said motor to be driven thereby; asupport structure on which said brush is carried; means mounting saidstructure movably on said frame to position said brush for rotationabout a substantially vertical axis and for enabling said structure andsaid brush to be moved upwardly relatively away from the surface to'beswept and downwardly for pressure engagement of said brush with saidsurface; operating means connected to said structure and being operablefor moving said supporting structure and said brush downwardly intopressure engagement of said brush with said surface; means for supplyingpower to said motor for operating the latter to rotate said brush;forceapplying means for subjecting said operating means to force for movingsaid structure and said brush downwardly to cause said brush to pressagainst said surface; and means interconnecting said power supplyingmeans and said force applying means and making the latter responsive toincreased resistance to rotation of said brush due to encounterngbuilt-up debris or an obstacle or the like for increasing the forceapplied to said force applying means and thereby increasing the pressureexerted by said brush on said surface.

4. Machine according to claim 3 including a device in saidinterconnecting means which is adjustable for varying the force appliedto said operating means and thereby varying the pressure exerted by saidbrush on said surface.

5. A mobile road or like surface sweeping machine comprising a frame; arotary hydraulic motor; a rotary brush operatively connected to saidmotor to be driven thereby; a supporting structure on which said motorand brush are carried; means mounting said structure movably on saidframe to position said motor and brush for rotation of the latter abouta substantially vertical axis and for enabling said structure and saidbrush to be moved upwardly relatively away from the surface to be sweptand downwardly for pressure engagement of said brush with said surface;a source of hydraulic pressure fluid; a hydraulic ram operativelyconnected to said supporting structure and being operable for movingsaid brush downwardly into pressure engagement with said surface; andfluid supply conduit means connecting said pressure source to said motorand to said ram with the inlet side of the motor communicating with saidram, whereby increase in resistance to rotation of said brush and motorcaused by the brushs encountering a build up of debris or an obstacle orthe like on said surface will increase the pressure in said supplyconduit means and cause said ram to force said structure and brushdownwardly and cause the brush to exert increased downward pressure onsaid surface.

6. Sweeping machine according to claim 5 including a valve in saidconduit means for controlling the pressure exerted by said brush on saidsurface.

7. Sweeping machine according to claim 6 in which said valve is in saidconduit means between said pressure source and said hydraulic motor, ispressure operated to open position to direct fluid flow to said motor,and is adjustable to vary the pressure required to open it.

8. Sweeping machine according to claim 7 in which said valve comprises aseat at the valve intake communicating with said pressure source; meansdefining a valve chamber communicating with said seat; a poppet valveelement movable in said chamber; and a spring yieldably urging saidpoppet valve element to close said seat, said conduit means including aconduit connection between said pressure source and said ram bypassingsaid valve and a conduit connection between said valve chamber and saidhydraulic motor, whereby pressure fluid delivered to said motor mustpass through-the pressure-opened valve.

9. Sweeping machine according to claim in which said hydraulic ramcomprises a cylinder and a double acting piston therein having a firstface of relatively large effective area, and a second face of relativelysmall effective area; and in which said fluid supply conduit meansincludes a first conduit connection leading from said source into saidcylinder on said first face side of said piston, and other conduitconnections leading from said source both to said cylinder on theopposite side of said piston and to the inlet side of said mo- I01.

10. Sweeping machine according to claim 5 including a spring biasingsaid structure and said brush upwardly.

l1. Sweeping machine according to claim 9 including a spring biasingsaid structure and said brush upwardly in concert with the applicationof fluid pressure on said second face of said piston.

12. Sweeping machine according to claim 9 including a pressureresponsive valve interposed between said source and said other conduitconnections, said valve having an element biased toward closed positionand being openable in response to pressure on the source side of saidvalve to permit fluid to flow under pressure through said other conduitconnections to said cylinder on said opposite side of said piston and tothe inlet side of said motor.

13. Sweeping machine according to claim 9 including a constantly openrate-of-flow control valve in said first conduit connection.

14. Sweeping machine according to claim 12 including a constantly openrate-of-flow control valve in said first conduit connection.

15. A mobile road or like surface sweeping machine comprising a frame; arotary hydraulic motor; a rotary brush operatively connected to saidmotor to be driven thereby; a supporting structure on which said motorand brush are carried; means mounting said structure movably on saidframe to position said motor and brush for rotation of the latter abouta substantially vertical axis and for enabling said structure and saidbrush to be moved upwardly relatively away from the surface to be sweptand downwardly for pressure engagement of said brush with said surface;a hydraulic ram comprising a cylinder component and a double actingpiston component relatively movable therein and having a first face ofrelatively large effective area and a second face of relatively smalleffective area; means connecting the movable one of said components tosaid supporting structure for tending to move said structure and brushupwardly under the action of fluid pressure on said second face of saidpiston component, and being operable for moving said support and brushdownwardly under the action of a fluid pressure on said first face ofsaid piston component; a source of fluid pressure; a main supply conduitconnected to said source; an exhaust conduit; service conduit meansconnected to said cylinder component on both sides of said pistoncomponent and to the inlet side of said motor; a motor dischargeconduit; and an operations control valve for selectively (1) connectingsaid main supply conduit to said service conduit means andsimultaneously connecting said exhaust conduit to said motor dischargeconduit, and (2) for selectively connecting said main supply conduit tosaid motor discharge conduit and connecting said service conduit meansto said exhaust conduit.

16. Sweeping machine according to claim 15 in which said operationscontrol valve includes settable means for blocking all fluid flow to orfrom said service conduit means and to or from said motor dischargeconduit, whereby no fluid power is transmitted to said motor and fluidis trapped in both ends of said cylinder component and prevents relativemovement of the cylinder and piston components, thereby holding saidstructure and brush stationary on said frame.

17. Sweeping machine according to claim 16 in which said source of fluidpressure is a pump, and in which said operations control valve settablemeans includes a passage for connecting said main supply to said exhaustconduit when said operations control valve settable means is set toblock fluid flow to or from said service conduit means and through saidmotor discharge conduit.

18. Sweeping machine according to claim 15 including a spring connectedto said structure and biasing the latter and said brush upwardly.

19. Sweeping machine according to claim 15 in which said service conduitmeans comprises a primary conduit connected to said main supply conduit;a first branch service conduit means providing constant communicationbetween said primary conduit and said cylinder componet on said firstface side of said piston component; a second branch service conduitmeans connected to said primary and to said motor and to said cylindercomponent on said second face side of said piston component; and apressure responsive valve in said second branch service conduit biasedto closed condition and being openable in response to fluid pressure insaid primary conduit.

20. A mobile road or like surface sweeping machine comprising a frame; abrush mounted on'said frame for vertical positioning movements and forrotation in contact with a surface to be swept when positioned in alower position; differentially acting hydraulic means for positioningsaid brush selectively in said lower position or in an upper positionout of contact with said surface; means for applying fluid pressure tosaid hydraulic means to exert relatively small force on said brush tourge the brush to said upper position, and to urge said brush oppositelyto said lower position with relatively large force overcoming saidrelatively small force, whereby to hold said brush in pressure contactwith said surface; and operations control means for discontinuingapplication of fluid pressure for exerting said relatively large forcewhile continuing the exertion of said relatively small force, therebyenabling the latter to move said brush to its upper position.

21. A mobile road or like surface sweeping machine comprising a frame; aboom; a rotary brush mounted on said boom for rotation about asubstantially vertical axis; means pivotally mounting said boom on saidframe at a first location for compounded simultaneous universal swingingmovements generally horizontally and generally vertically to therebymove said brush outwardly and downwardly from a retracted elevatedposition relatively close to a side of said frame to a lowered positionrelatively wide of said frame and in brushing engagement with thesurface to be swept; and a single hydraulic ram including a cylindercomponent and a piston component therein for causing said boom toperform said compounded simultaneous movements, said brush being mountedon said boom at a second location spaced from said first location, oneof said ram coinponents being pivoted universally to said frame at athird location thereon spaced from said first location, and the other ofsaid ram components being pivoted to said boom at a location spaced fromsaid first location.

22. Machine according to claim 21 in which said third location is spacedboth vertically and horizontally from said first location.

23. Machine according to claim 22 in which said third location is spacedabove said first location and is spaced horizontally from said firstlocation toward the center of said frame.

24. Machine according to claim 23 further including a spring anchored tosaid frame and connected to said boom and being loaded in a direction tourge said boom to swing about said first location upwardly andhorizontally inwardly relatively to the center of said frame inopposition to the extension of said ram' 25. Machine according to claim24 in which said spring is a tension spring which is anchored at one endto said frame at a point above and horizontally between said first andthird locations, and is connected at its other end to said boom adjacentto said brush.

26. Machine according to claim 25 including means for adjusting theloading of said spring.

27. Machine according to claim 23 in which said hydraulic ram pistoncomponent is double acting with one face of larger area than the otherface thereof, said machine further including a source of pressure fluid;conduit means for delivering fluid under pressure to said cylindercomponent at both faces of said piston component, the application offluid pressure to said larger area face of said piston component drivingthe latter to extend said ram in opposition to the application of fluidpressure to said other face of said piston component.

28. Machine according to claim 27 including valve means for selectivelyeffecting delivery of fluid to said cylinder component on both sides ofsaid piston component and alternatively relieving fluid pressure fromsaid cylinder component on the side of the larger piston component facearea while continuing to apply fluid pressure in said cylinder componenton the opposite face of said piston component, whereby to retract saidram and simultaneously swing said boom inwardly with respect to saidframe and upwardly away from said surface.

29. Machine according to claim 28 including a hydraulic motor mounted onsaid boom for driving said brush rotatably; and a conduit connection fordelivering a flow of pressure fluid from said source to said motor whenpressure fluid is delivered to said cylinder component at both sides ofsaid piston component.

1. A mobile road or like surface sweeping machine comprising a frame; abrush mounted on said frame for rotation in contact with the surface tobe swept; a motor for rotating said brush; brush positioning means formoving said brush downwardly to press on said surface; means fordelivering power to said motor; and force applying means associated withsaid power delivering means and connected to said brush positioningmeans for operating the latter to move said brush downwardly and beingresponsive to a condition in the input to said motor for applyingincreased force to said brush positioning means when said brushencounters builtup debris or an obstacle or the like with resultantresistance to rotation of said brush and running of said motor, saidapplication of increased force to the brush positioning means pressingthe brush with increased firmness against said surface thereby better toensure sweeping of the debris, obstacle or the like.
 2. Machineaccording to claim 1 in which said motor and said force applying meansare fluid pressure operated and in which saId force applying means isresponsive to an increase in pressure of fluid in the fluid pressureoperated motor inlet supply for applying said increased force to saidbrush positioning means.
 3. A mobile road or like surface sweepingmachine comprising a frame; a motor; a rotary brush connected to saidmotor to be driven thereby; a support structure on which said brush iscarried; means mounting said structure movably on said frame to positionsaid brush for rotation about a substantially vertical axis and forenabling said structure and said brush to be moved upwardly relativelyaway from the surface to be swept and downwardly for pressure engagementof said brush with said surface; operating means connected to saidstructure and being operable for moving said supporting structure andsaid brush downwardly into pressure engagement of said brush with saidsurface; means for supplying power to said motor for operating thelatter to rotate said brush; force applying means for subjecting saidoperating means to force for moving said structure and said brushdownwardly to cause said brush to press against said surface; and meansinterconnecting said power supplying means and said force applying meansand making the latter responsive to increased resistance to rotation ofsaid brush due to encounterng built-up debris or an obstacle or the likefor increasing the force applied to said force applying means andthereby increasing the pressure exerted by said brush on said surface.4. Machine according to claim 3 including a device in saidinterconnecting means which is adjustable for varying the force appliedto said operating means and thereby varying the pressure exerted by saidbrush on said surface.
 5. A mobile road or like surface sweeping machinecomprising a frame; a rotary hydraulic motor; a rotary brush operativelyconnected to said motor to be driven thereby; a supporting structure onwhich said motor and brush are carried; means mounting said structuremovably on said frame to position said motor and brush for rotation ofthe latter about a substantially vertical axis and for enabling saidstructure and said brush to be moved upwardly relatively away from thesurface to be swept and downwardly for pressure engagement of said brushwith said surface; a source of hydraulic pressure fluid; a hydraulic ramoperatively connected to said supporting structure and being operablefor moving said brush downwardly into pressure engagement with saidsurface; and fluid supply conduit means connecting said pressure sourceto said motor and to said ram with the inlet side of the motorcommunicating with said ram, whereby increase in resistance to rotationof said brush and motor caused by the brush''s encountering a build upof debris or an obstacle or the like on said surface will increase thepressure in said supply conduit means and cause said ram to force saidstructure and brush downwardly and cause the brush to exert increaseddownward pressure on said surface.
 6. Sweeping machine according toclaim 5 including a valve in said conduit means for controlling thepressure exerted by said brush on said surface.
 7. Sweeping machineaccording to claim 6 in which said valve is in said conduit meansbetween said pressure source and said hydraulic motor, is pressureoperated to open position to direct fluid flow to said motor, and isadjustable to vary the pressure required to open it.
 8. Sweeping machineaccording to claim 7 in which said valve comprises a seat at the valveintake communicating with said pressure source; means defining a valvechamber communicating with said seat; a poppet valve element movable insaid chamber; and a spring yieldably urging said poppet valve element toclose said seat, said conduit means including a conduit connectionbetween said pressure source and said ram by-passing said valve and aconduit connection between said valve chamber and said hydraulic motor,whereby pressure fluid delivered to said motor must pass through thepressure-opeNed valve.
 9. Sweeping machine according to claim 5 in whichsaid hydraulic ram comprises a cylinder and a double acting pistontherein having a first face of relatively large effective area, and asecond face of relatively small effective area; and in which said fluidsupply conduit means includes a first conduit connection leading fromsaid source into said cylinder on said first face side of said piston,and other conduit connections leading from said source both to saidcylinder on the opposite side of said piston and to the inlet side ofsaid motor.
 10. Sweeping machine according to claim 5 including a springbiasing said structure and said brush upwardly.
 11. Sweeping machineaccording to claim 9 including a spring biasing said structure and saidbrush upwardly in concert with the application of fluid pressure on saidsecond face of said piston.
 12. Sweeping machine according to claim 9including a pressure responsive valve interposed between said source andsaid other conduit connections, said valve having an element biasedtoward closed position and being openable in response to pressure on thesource side of said valve to permit fluid to flow under pressure throughsaid other conduit connections to said cylinder on said opposite side ofsaid piston and to the inlet side of said motor.
 13. Sweeping machineaccording to claim 9 including a constantly open rate-of-flow controlvalve in said first conduit connection.
 14. Sweeping machine accordingto claim 12 including a constantly open rate-of-flow control valve insaid first conduit connection.
 15. A mobile road or like surfacesweeping machine comprising a frame; a rotary hydraulic motor; a rotarybrush operatively connected to said motor to be driven thereby; asupporting structure on which said motor and brush are carried; meansmounting said structure movably on said frame to position said motor andbrush for rotation of the latter about a substantially vertical axis andfor enabling said structure and said brush to be moved upwardlyrelatively away from the surface to be swept and downwardly for pressureengagement of said brush with said surface; a hydraulic ram comprising acylinder component and a double acting piston component relativelymovable therein and having a first face of relatively large effectivearea and a second face of relatively small effective area; meansconnecting the movable one of said components to said supportingstructure for tending to move said structure and brush upwardly underthe action of fluid pressure on said second face of said pistoncomponent, and being operable for moving said support and brushdownwardly under the action of a fluid pressure on said first face ofsaid piston component; a source of fluid pressure; a main supply conduitconnected to said source; an exhaust conduit; service conduit meansconnected to said cylinder component on both sides of said pistoncomponent and to the inlet side of said motor; a motor dischargeconduit; and an operations control valve for selectively (1) connectingsaid main supply conduit to said service conduit means andsimultaneously connecting said exhaust conduit to said motor dischargeconduit, and (2) for selectively connecting said main supply conduit tosaid motor discharge conduit and connecting said service conduit meansto said exhaust conduit.
 16. Sweeping machine according to claim 15 inwhich said operations control valve includes settable means for blockingall fluid flow to or from said service conduit means and to or from saidmotor discharge conduit, whereby no fluid power is transmitted to saidmotor and fluid is trapped in both ends of said cylinder component andprevents relative movement of the cylinder and piston components,thereby holding said structure and brush stationary on said frame. 17.Sweeping machine according to claim 16 in which said source of fluidpressure is a pump, and in which said operations control valve settablemeans includes a passage for connecting said main Supply to said exhaustconduit when said operations control valve settable means is set toblock fluid flow to or from said service conduit means and through saidmotor discharge conduit.
 18. Sweeping machine according to claim 15including a spring connected to said structure and biasing the latterand said brush upwardly.
 19. Sweeping machine according to claim 15 inwhich said service conduit means comprises a primary conduit connectedto said main supply conduit; a first branch service conduit meansproviding constant communication between said primary conduit and saidcylinder componet on said first face side of said piston component; asecond branch service conduit means connected to said primary and tosaid motor and to said cylinder component on said second face side ofsaid piston component; and a pressure responsive valve in said secondbranch service conduit biased to closed condition and being openable inresponse to fluid pressure in said primary conduit.
 20. A mobile road orlike surface sweeping machine comprising a frame; a brush mounted onsaid frame for vertical positioning movements and for rotation incontact with a surface to be swept when positioned in a lower position;differentially acting hydraulic means for positioning said brushselectively in said lower position or in an upper position out ofcontact with said surface; means for applying fluid pressure to saidhydraulic means to exert relatively small force on said brush to urgethe brush to said upper position, and to urge said brush oppositely tosaid lower position with relatively large force overcoming saidrelatively small force, whereby to hold said brush in pressure contactwith said surface; and operations control means for discontinuingapplication of fluid pressure for exerting said relatively large forcewhile continuing the exertion of said relatively small force, therebyenabling the latter to move said brush to its upper position.
 21. Amobile road or like surface sweeping machine comprising a frame; a boom;a rotary brush mounted on said boom for rotation about a substantiallyvertical axis; means pivotally mounting said boom on said frame at afirst location for compounded simultaneous universal swinging movementsgenerally horizontally and generally vertically to thereby move saidbrush outwardly and downwardly from a retracted elevated positionrelatively close to a side of said frame to a lowered positionrelatively wide of said frame and in brushing engagement with thesurface to be swept; and a single hydraulic ram including a cylindercomponent and a piston component therein for causing said boom toperform said compounded simultaneous movements, said brush being mountedon said boom at a second location spaced from said first location, oneof said ram components being pivoted universally to said frame at athird location thereon spaced from said first location, and the other ofsaid ram components being pivoted to said boom at a location spaced fromsaid first location.
 22. Machine according to claim 21 in which saidthird location is spaced both vertically and horizontally from saidfirst location.
 23. Machine according to claim 22 in which said thirdlocation is spaced above said first location and is spaced horizontallyfrom said first location toward the center of said frame.
 24. Machineaccording to claim 23 further including a spring anchored to said frameand connected to said boom and being loaded in a direction to urge saidboom to swing about said first location upwardly and horizontallyinwardly relatively to the center of said frame in opposition to theextension of said ram.
 25. Machine according to claim 24 in which saidspring is a tension spring which is anchored at one end to said frame ata point above and horizontally between said first and third locations,and is connected at its other end to said boom adjacent to said brush.26. Machine according to claim 25 including means for adjusting theloading of said spring.
 27. Machine according to claim 23 in which saidhydraulic ram piston component is double acting with one face of largerarea than the other face thereof, said machine further including asource of pressure fluid; conduit means for delivering fluid underpressure to said cylinder component at both faces of said pistoncomponent, the application of fluid pressure to said larger area face ofsaid piston component driving the latter to extend said ram inopposition to the application of fluid pressure to said other face ofsaid piston component.
 28. Machine according to claim 27 including valvemeans for selectively effecting delivery of fluid to said cylindercomponent on both sides of said piston component and alternativelyrelieving fluid pressure from said cylinder component on the side of thelarger piston component face area while continuing to apply fluidpressure in said cylinder component on the opposite face of said pistoncomponent, whereby to retract said ram and simultaneously swing saidboom inwardly with respect to said frame and upwardly away from saidsurface.
 29. Machine according to claim 28 including a hydraulic motormounted on said boom for driving said brush rotatably; and a conduitconnection for delivering a flow of pressure fluid from said source tosaid motor when pressure fluid is delivered to said cylinder componentat both sides of said piston component.